Many times, I have purchased a new thermostat which does not have a bleeder valve on the top of it, I would overheat at random times! got the right t-stat and all was well. With a closed system, I have found this VERY important. If just drilling a hole in the thing, this will help some times. But I would get the type which has it.FYI.!!!

I have a 89 I just bought 2 weeks ago. I paid the women and got the title. I didn't notice the puddle of coolant in the tar paper like stuff at the bottom of the engine compartment until I got home. I looked for a leak and did not find one so I figured it was from a recent repair as it had new Gates hoses on it.

I also noticed the heater wasn't working all that well so the first thing I did was replace the T-stat. I burped the system like I read on here. It was fine until today while I was drying the engine after some engine degreasing The pressure bottle started spewing coolant and coolant was running from underneath the radiator. Once again I cannot find where the leak in the radiator is.

I filled up the tank and its been running for the past hour with no issues. Whats up?

I have a grand Cherokee 05 just did water pump and thermostat and it still over heating why??? I did notice inside on windshield had some condensation on right side could it be my heater core thats making it over heat????